Answer this question truthfully
### Question: What causes Hay fever?
### Response: An allergen is something that triggers an allergy. When a person with allergic rhinitis breathes in an allergen such as pollen or dust, the body releases chemicals, including histamine. This causes allergy symptoms such as itching, swelling, and mucus production.
Hay fever involves an allergic reaction to pollen. (A similar reaction occurs with allergy to mold, animal dander, dust, and similar inhaled allergens.)
The pollens that cause hay fever vary from person to person and from region to region. Large, visible pollens are seldom responsible for hay fever. Tiny, hard to see pollens more often cause hay fever. Examples of plants commonly responsible for hay fever include:
Trees (deciduous and evergreen) Grasses Ragweed
The amount of pollen in the air can play a role in whether hay fever symptoms develop. Hot, dry, windy days are more likely to have increased amounts of pollen in the air than cool, damp, rainy days when most pollen is washed to the ground.
Some disorders may be associated with allergies. These include eczema and asthma.
Allergies are common. Your genes and environment may make you more prone to allergies.